Radical chemistry and VOCs-NOx-O3-nitrate sensitivity in the polluted atmosphere of a suburban site in the North China Plain.

In this study, the chemical mechanisms of O3 and nitrate formation as well as the control strategy were investigated based on extensive observations in Tai'an city in the NCP and an observation-constrained box model. The results showed that O3 pollution was severe with the maximum hourly O3 concentration reaching 150 ppb. Higher O3 concentration was typically accompanied by higher PM2.5 concentrations, which could be ascribed to the common precursors of VOCs and NOx. The modeled averaged peak concentrations of OH, HO2, and RO2 were relatively higher compared to previous observations, indicating strong atmospheric oxidation capacity in the study area. The ROx production rate increased from 2.8 ppb h-1 to 5 ppb h-1 from the clean case to the heavily polluted case and was dominated by HONO photolysis, followed by HCHO photolysis. The contribution of radical-self combination to radical termination gradually exceeded NO2 + OH from clean to polluted cases, indicating that O3 formation shifted to a more NOx-limited regime. The O3 production rate increased from 14 ppb h-1 to 22 ppb h-1 from clean to heavily polluted cases. The relative incremental reactivity (RIR) results showed that VOCs and NOx had comparable RIR values during most days, which suggested that decreasing VOCs or NOx was both effective in alleviating O3 pollution. In addition, HCHO, with the largest RIR value, made important contribution to O3 production. The Empirical Kinetic Modeling Approach (EKMA) revealed that synergistic control of O3 and nitrate can be achieved by decreasing both NOx and VOCs emissions (e.g., alkenes) with the ratio of 3:1. This study emphasized the importance of NOx abatement for the synergistic control of O3 and nitrate pollution in the Tai'an area as the sustained emissions control has shifted the O3 and nitrate formation to a more NOx-limited regime.

Laser-Induced Pd-PdO/rGO Catalysts for Enhanced Electrocatalytic Conversion of Nitrate into Ammonia.

Electrochemical reduction of nitrate to ammonia (eNO3RR) is proposed as a sustainable solution for high-rate ammonia synthesis under ambient conditions. The complex, multistep eNO3RR mechanism necessitates the use of a catalyst for the complete conversion of nitrate to ammonia. Our research focuses on developing a novel Pd-PdO doped in a reduced graphene oxide (rGO) composite catalyst synthesized via a laser-assisted one-step technique. This catalyst demonstrates dual functionality: palladium (Pd) boosts hydrogen adsorption, while its oxide (PdO) demonstrates considerable nitrogen adsorption affinity and exhibits a maximum ammonia yield of 5456.4 ± 453.4 µg/h/cm2 at -0.6 V vs reversible hydrogen electrode (RHE), with significant yields for nitrite and hydroxylamine under ambient conditions in a nitrate-containing alkaline electrolyte. At a lower potential of -0.1 V, the catalyst exhibited a minimal hydrogen evolution reaction of 3.1 ± 2.2% while achieving high ammonia selectivity (74.9 ± 4.4%), with the balance for nitrite and hydroxylamine. Additionally, the catalyst's stability and activity can be regenerated through the electrooxidation of Pd.

High Ammonia Yield Rate from Dilute Nitrate Solutions Using a Cu(100)-Rich Foil: A Step Closer to Large-Scale Production.

The electrochemical reduction of nitrate (NO3-) ions to ammonia (NH3) provides an alternative method to eliminate harmful NO3- pollutants in water as well as to produce highly valuable NH3 chemicals. The NH3 yield rate however is still limited to the µmol h-1 cm-2 range when dealing with dilute NO3- concentrations found in waste streams. Copper (Cu) has attracted much attention because of its unique ability to effectively convert NO3- to NH3. We have reported a simple and scalable electrochemical method to produce a Cu foil having its surface covered with a porous Cu nanostructure enriched with (100) facets, which efficiently catalyzes NO3- to NH3. The Cu(100)-rich electrocatalyst showed a very high NH3 production rate of 1.1 mmol h-1 cm-2 in NO3- concentration as low as 14 mM NO3-, which is 4-5 times higher than the best-reported values. Increasing the NO3- concentration (140 mM) resulted in an NH3 production yield rate of 3.34 mmol h-1 cm-2. The durability test conducted for this catalyst foil in a flow cell system showed greater than 100 h stability with a Faradaic efficiency greater than 98%, demonstrating its potential to be used on an industrially relevant scale. Further, density functional theory (DFT) calculations have been performed to understand the better catalytic activity of Cu(100) compared to Cu(111) facets toward NO3-RR.

Effects of acute beetroot juice intake on performance, maximal oxygen uptake, and ventilatory efficiency in well-trained master rowers: a randomized, double-blinded crossover study.

BACKGROUND: Beetroot juice (BRJ) intake has been considered a practical nutritional strategy among well-trained athletes. This study aimed to assess the effects of BRJ intake on performance, cardiorespiratory and metabolic variables during a simulated 2000-meter rowing ergometer test in well-trained master rowers. METHOD: Ten well-trained male master rowers (30-48 years) participated in a randomized, double-blind, crossover design for 3 weeks. In the first week, a researcher explained all the experimental procedures to the participants. In the next two weeks, the participants were tested in 2 rowing ergometer sessions, separated from each other by a 7-day washout period. In both strictly identical sessions, the participants randomly drank BRJ or placebo (PL) 3 hours before the start of the tests. Subsequently, the participants carried out the 2000-meter rowing ergometer tests. Oxygen saturation and blood lactate measurements were performed before starting (pretest) and at the end of the test (posttest). Performance parameters and cardiorespiratory variables were recorded during the rowing ergometer test. RESULTS: An improvement in time trial performance was observed, with a mean difference of 4 seconds (90% confidence limits ± 3.10; p ≤ 0.05) compared to PL. Relative and absolute maximaloxygenuptakeV˙O2max increased (mean difference of 2.10 mL·kg-1·min-1, 90% confidence limits ± 1.80; mean difference of 0.16 L·min-1 90% confidence limits ± 0.11, respectively; p ≤ 0.05) compared to PL. No ergogenic effect was observed on ventilatory efficiency and blood lactate concentrations after BRJ intake. CONCLUSION: Acute BRJ intake may improve time trial performance as well as V˙O2max in well-trained master rowers. However, BRJ does not appear to improve ventilatory efficiency.

Solar-Powered Gram-Scale Ammonia Production from Nitrate.

The photoelectrochemical (PEC) method has the potential to be an attractive route for converting and storing solar energy as chemical bonds. In this study, a maximum NH3 production yield of 1.01 g L-1 with a solar-to-ammonia conversion efficiency of 8.17% through the photovoltaic electrocatalytic (PV-EC) nitrate (NO3 -) reduction reaction (NO3 -RR) is achieved, using silicon heterojunction solar cell technology. Additionally, the effect of tuning the operation potential of the PV-EC system and its influence on product selectivity are systematically investigated. By using this unique external resistance tuning approach in the PV-EC system, ammonia production through nitrate reduction performance from 96 to 360 mg L-1 is enhanced, a four-fold increase. Furthermore, the NH3 is extracted as NH4Cl powder using acid stripping, which is essential for storing chemical energy. This work demonstrates the possibility of tuning product selectivity in PV-EC systems, with prospects toward pilot scale on value-added product synthesis.

Membraneless Electrochemical Synthesis Strategy toward Nitrate-to-Ammonia Conversion.

Electroreduction of nitrate (NO3RR) to ammonia in membraneless electrolyzers is of great significance for reducing the cost and saving energy consumption. However, severe chemical crossover with side reactions makes it challenging to achieve ideal electrolysis. Herein, we propose a general strategy for efficient membraneless ammonia synthesis by screening NO3RR catalysts with inferior oxygen reduction activity and matching the counter electrode (CE) with good oxygen evolution activity while blocking anodic ammonia oxidation. Consequently, screening the available Co-Co system, the membraneless NO3--to-NH3 conversion performance was significantly higher than H-type cells using costly proton-exchange membranes. At 200 mA cm-2, the full-cell voltage of the membraneless system (∼2.5 V) is 4 V lower than that of the membrane system (∼6.5 V), and the savings are 61.4 kW h (or 56.9%) per 1 kg NH3 produced. A well-designed pulse process, inducing reversible surface reconstruction that in situ generates and restores the active Co(III) species at the working electrode and forms favorable Co3O4/CoOOH at the CE, further significantly improves NO3--to-NH3 conversion and blocks side reactions. A maximum NH3 yield rate of 1500.9 µmol cm-2 h-1 was achieved at -0.9 V (Faraday efficiency 92.6%). This pulse-coupled membraneless strategy provides new insights into design complex electrochemical synthesis.

Evaluation on photocatalytic activity of bismuth nitrate derived materials at different calcination temperatures using paper microzones method.

Our work reveals for the first time that directly calcined bismuth nitrate derivatives (BNDs) possess significant photocatalytic activity towards rhodamine B (RhB). As the calcination temperature increased, the Bi(NO3)3·5H2O powder gradually ruptured and transformed into different bismuth nitrate products and their mixtures, finally into stable α-Bi2O3 at 500 °C. Among them, BNDs-100 could achieve 100 % photocatalytic degradation of 10 mg/L RhB solution under UV irradiation for 6 min. The ImageJ-led paper microzones (PMZs) method is introduced for the first time into the performance evaluation process of photocatalysts, which can achieve the green chemistry pathway and the rapid evaluation of different catalysts. The accuracy of the results of the PMZs method relative to the spectrophotometric method was up to 91.14 %, which has a better reliability and is suitable for qualitative analysis, and a certain ability when used for quantitative analysis. The results showed that the PMZs method was used to assess the photocatalytic degradation of rhodamine B by bismuth nitrate-derived materials at different calcination temperatures with well reliability, and the preparation of BNDs by direct calcination was a simple and effective strategy.

Dissecting the Photochemical Reactivity of Metal Ions during Atmospheric Nitrate Transformations on Photoactive Mineral Dust.

Dissecting the photochemical reactivity of metal ions is a significant contribution to understanding secondary pollutant formation, as they have a role to be reckoned with atmospheric chemistry. However, their photochemical reactivity has received limited attention within the active nitrogen cycle, particularly at the gas-solid interface. In this study, we delve into the contribution of magnesium ion (Mg2+) and ferric ion (Fe3+) to nitrate decomposition on the surface of photoactive mineral dust. Under simulated sunlight irradiation, the observed NOX production rate differs by an order of magnitude in the presence of Mg2+ (6.02 × 10-10 mol s-1) and Fe3+ (2.07 × 10-11 mol s-1). The markedly decreased fluorescence lifetime induced by Mg2+ and the change in the valence of Fe3+ revealed that Mg2+ and Fe3+ significantly affect the concentration of nitrate decomposition products by distinct photochemical reactivity with photogenerated electrons. Mg2+ promotes NOX production by accelerating charge transfer, while Fe3+ hinders nitrate decomposition by engaging in a redox cyclic reaction with Fe2+ to consume photogenerated carriers continuously. Furthermore, when Fe3+ coexists with other metal ions (e.g., Mg2+, Ca2+, Na+, and K+) and surpasses a proportion of approximately 12%, the photochemical reactivity of Fe3+ tends to be dominant in depleting photogenerated electrons and suppressing nitrate decomposition. Conversely, below this threshold, the released NOX concentration increases sharply as the proportion of Fe3+ decreases. This research offers valuable insights into the role of metal ions in nitrate transformation and the generation of reactive nitrogen species, contributing to a deep understanding of atmospheric photochemical reactions.

Dynamic changes in mRNA nucleocytoplasmic localization in the nitrate response of Arabidopsis roots.

Nitrate is a nutrient and signal that regulates gene expression. The nitrate response has been extensively characterized at the organism, organ, and cell-type-specific levels, but intracellular mRNA dynamics remain unexplored. To characterize nuclear and cytoplasmic transcriptome dynamics in response to nitrate, we performed a time-course expression analysis after nitrate treatment in isolated nuclei, cytoplasm, and whole roots. We identified 402 differentially localized transcripts (DLTs) in response to nitrate treatment. Induced DLT genes showed rapid and transient recruitment of the RNA polymerase II, together with an increase in the mRNA turnover rates. DLTs code for genes involved in metabolic processes, localization, and response to stimulus indicating DLTs include genes with relevant functions for the nitrate response that have not been previously identified. Using single-molecule RNA FISH, we observed early nuclear accumulation of the NITRATE REDUCTASE 1 (NIA1) transcripts in their transcription sites. We found that transcription of NIA1, a gene showing delayed cytoplasmic accumulation, is rapidly and transiently activated; however, its transcripts become unstable when they reach the cytoplasm. Our study reveals the dynamic localization of mRNAs between the nucleus and cytoplasm as an emerging feature in the temporal control of gene expression in response to nitrate treatment in Arabidopsis roots.

Effects of Ionic Interferents on Electrocatalytic Nitrate Reduction: Mechanistic Insight.

Nitrate, a prevalent water pollutant, poses substantial public health concerns and environmental risks. Electrochemical reduction of nitrate (eNO3RR) has emerged as an effective alternative to conventional biological treatments. While extensive lab work has focused on designing efficient electrocatalysts, implementation of eNO3RR in practical wastewater settings requires careful consideration of the effects of various constituents in real wastewater. In this critical review, we examine the interference of ionic species commonly encountered in electrocatalytic systems and universally present in wastewater, such as halogen ions, alkali metal cations, and other divalent/trivalent ions (Ca2+, Mg2+, HCO3-/CO32-, SO42-, and PO43-). Notably, we categorize and discuss the interfering mechanisms into four groups: (1) loss of active catalytic sites caused by competitive adsorption and precipitation, (2) electrostatic interactions in the electric double layer (EDL), including ion pairs and the shielding effect, (3) effects on the selectivity of N intermediates and final products (N2 or NH3), and (4) complications by the hydrogen evolution reaction (HER) and localized pH on the cathode surface. Finally, we summarize the competition among different mechanisms and propose future directions for a deeper mechanistic understanding of ionic impacts on eNO3RR.

Changes in source composition of wet nitrate deposition after air pollution control in a typical area of Southeast China.

In recent years, China has adopted numerous policies and regulations to control NOx emissions to further alleviate the adverse impacts of NO3--N deposition. However, the variation in wet NO3--N deposition under such policies is not clear. In this study, the southeastern area, with highly developed industries and traditional agriculture, was selected to explore the variation in NO3--N deposition and its sources changes after such air pollution control through field observation and isotope tracing. Results showed that the annual mean concentrations of NO3--N in precipitation were 0.67 mg L-1 and 0.54 mg L-1 in 2014-2015 and 2021-2022, respectively. The average wet NO3--N depositions in 2014-2015 and 2021-2022 was 7.76 kg N ha-1 yr-1 and 5.03 kg N ha-1 yr-1, respectively, indicating a 35% decrease. The δ15N-NO3- and δ18O-NO3- values were lower in warm seasons and higher in cold seasons, and both showed a lower trend in 2021-2022 compared with 2014-2015. The Bayesian model results showed that the NOx emitted from coal-powered plants contributed 53.6% to wet NO3--N deposition, followed by vehicle exhaust (22.9%), other sources (17.1%), and soil emissions (6.4%) during 2014-2015. However, the contribution of vehicle exhaust (33.3%) overpassed the coal combustion (32.3%) and followed by other sources (25.4%) and soil emissions (9.0%) in 2021-2022. Apart from the control of air pollution, meteorological factors such as temperature, precipitation, and solar radiation are closely related to the changes in atmospheric N transformation and deposition. The results suggest phased achievements in air pollution control and that more attention should be paid to the control of motor vehicle exhaust pollution in the future, at the same time maintaining current actions and supervision of coal-powered plants.

Lot-to-lot variation in the microbiota during the brewing process of kimoto-type Japanese rice wine.

Kimoto-type Japanese rice wine (sake) has a wide variety of flavors, as the predominant microbes, including lactic acid bacteria (LAB) and nitrate-reducing bacteria, that spontaneously proliferate in the fermentation starter vary depending on the brewery. In this study, we traced the microbiota in four lots of starters manufactured in a newly established brewery and evaluated the lot-to-lot variation and characteristics of the microbiota in the brewery. The results of a 16S ribosomal RNA amplicon analysis showed that the starters brewed in the second brewing year had a more diverse microbiota than those in the first brewing year. Among the LAB predominated at the middle production stage, lactococci, including Leuconostoc spp., were detected in all the lots, while lactobacilli predominated for the first time in the second year. These results suggest that repeated brewing increased microbial diversity and altered the microbial transition pattern in the kimoto-style fermentation starters. Phylogenetic analyses for the LAB isolates from each starter identified Leuconostoc suionicum, Leuconostoc citreum, and Leuconostoc mesenteroides as predominant lactococci as well as a unique lactobacillus in place of Latilactobacillus sakei. We also found that a rice koji-derived Staphylococcus gallinarum with nitrate-reducing activity was generally predominant during the early production stage, suggesting that there was a case in which staphylococci played a role in nitrite production in the starters. These findings are expected to contribute to the understanding of the diversity of microbiota in kimoto-type sake brewing and enable control of the microbiota for consistent sake quality.

Boosting Electrochemical Nitrate Reduction at Low Concentrations Through Simultaneous Electronic States Regulation and Proton Provision.

Electrochemically converting nitrate (NO3 -) into ammonia (NH3) has emerged as an alternative strategy for NH3 production and effluent treatment. Nevertheless, the electroreduction of dilute NO3 - is still challenging due to the competitive adsorption between various aqueous species and NO3 -, and unfavorable water dissociation providing *H. Herein, a new tandem strategy is proposed to boost the electrochemical nitrate reduction reaction (NO3RR) performance of Cu nanoparticles supported on single Fe atoms dispersed N-doped carbon (Cu@Fe1-NC) at dilute NO3 - concentrations (≤100 ppm NO3 --N). The optimized Cu@Fe1-NC presents a FENH3 of 97.7% at -0.4 V versus RHE, and a significant NH3 yield of 1953.9 mmol h-1 gCu -1 at 100 ppm NO3 --N, a record-high activity for dilute NO3RR. The metal/carbon heterojunctions in Cu@Fe1-NC enable a spontaneous electron transfer from Cu to carbon substrate, resulting in electron-deficient Cu. As a result, the electron-deficient Cu facilitates the adsorption of NO3 - compared with the pristine Cu. The adjacent atomic Fe sites efficiently promote water dissociation, providing abundant *H for the hydrogenation of *NOx e at Cu sites. The synergistic effects between Cu and single Fe atom sites simultaneously decrease the energy barrier for NO3 - adsorption and hydrogenation, thereby enhancing the overall activity of NO3 - reduction.

Recovery of ecosystems pollution by contaminants of potential concern using phytoremediation techniques.

Phytoremediation is a technology that uses plants to break down, remove, and immobilize contaminants in surface water, shallow groundwater, and sediment to achieve cost savings compared with conventional treatments. This study describes a marshy land on an explosives manufacturing site in India that consistently reported elevated concentrations of nitrates, nitrites, ammonia, perchlorate, and lead (contaminants of potential concern-CoPC). The study also illustrates the potential for addressing the human health and environmental risks associated with the explosives manufacturing industrsy in India using innovative, sustainable, and carbon-neutral techniques. This work focuses on reconstructed marshy lands, desedimentation, microwatershed management, and phytoremediation using Phragmites and Vetiveria species (also known as vetiver) to reduce contaminants in surface water and groundwater, improve stormwater management and carbon capture, and increase natural capital like biodiversity. The results obtained during the trial indicate that the selected indigenous species are effective and can be used to remediate sediment and shallow groundwater for many CoPC in tropical climates. Integr Environ Assess Manag 2024;00:1-16. © 2024 SETAC.

Application of artificial intelligence in modeling of nitrate removal process using zero-valent iron nanoparticles-loaded carboxymethyl cellulose.

This study explores nitrate reduction in aqueous solutions using carboxymethyl cellulose loaded with zero-valent iron nanoparticles (Fe0-CMC). The structures of this nano-composite were characterized using various techniques. Based on the characterization results, the specific surface area of Fe0-CMC measured by the Brunauer-Emmett-Teller analysis were 39.6 m2/g. In addition, Scanning Electron Microscopy images displayed that spherical nano zero-valent iron particles (nZVI) with an average particle diameter of 80 nm are surrounded by carboxymethyl cellulose and no noticeable aggregates were detected. Batch experiments assessed Fe0-CMC's effectiveness in nitrate removal under diverse conditions including different adsorbent dosages (Cs, 2-10 mg/L), contact time (t, 10-1440 min), initial pH (pHi, 2-10), temperature (T, 10-55 °C), and initial concentration of nitrate (C0, 10-500 mg/L). Results indicated decreased removal with higher initial pHi and C0, while increased Cs and T enhanced removal. The study of nitrate removal mechanism by Fe0-CMC revealed that the redox reaction between immobilized nZVI on the CMC surface and nitrate ions was responsible for nitrate removal, and the main product of this reaction was ammonium, which was subsequently completely removed by the synthesized nanocomposite. In addition, a stable deviation quantum particle swarm optimization algorithm (SD-QPSO) and a least square error method were employed to train the ANFIS parameters. To demonstrate model performance, a quadratic polynomial function was proposed to display the performance of the SD-QPSO algorithm in which the constant parameters were optimized through the SD-QPSO algorithm. Sensitivity analysis was conducted on the proposed quadratic polynomial function by adding a constant deviation and removing each input using two different strategies. According to the sensitivity analysis, the predicted removal efficiency was most sensitive to changes in pHi, followed by Cs, T, C0, and t. The obtained results underscore the potential of the ANFIS model (R2 = 0.99803, RMSE = 0.9888), and polynomial function (R2 = 0.998256, RMSE = 1.7532) as accurate and efficient alternatives to time-consuming laboratory measurements for assessing nitrate removal efficiency. These models can offer rapid insights and predictions regarding the impact of various factors on the process, saving both time and resources.

Genomic organization and expression profiles of nitrogen assimilation genes in Glycine max.

Background: Glutamine synthetase (GS), glutamate synthase (GOGAT), and nitrate reductase (NR) are key enzymes involved in nitrogen assimilation and metabolism in plants. However, the systematic analysis of these gene families lacked reports in soybean (Glycine max (L.) Merr.), one of the most important crops worldwide. Methods: In this study, we performed genome-wide identification and characterization of GS, GOGAT, and NR genes in soybean under abiotic and nitrogen stress conditions. Results: We identified a total of 10 GS genes, six GOGAT genes, and four NR genes in the soybean genome. Phylogenetic analysis revealed the presence of multiple isoforms for each gene family, indicating their functional diversification. The distribution of these genes on soybean chromosomes was uneven, with segmental duplication events contributing to their expansion. Within the nitrogen assimilation genes (NAGs) group, there was uniformity in the exon-intron structure and the presence of conserved motifs in NAGs. Furthermore, analysis of cis-elements in NAG promoters indicated complex regulation of their expression. RT-qPCR analysis of seven soybean NAGs under various abiotic stresses, including nitrogen deficiency, drought-nitrogen, and salinity, revealed distinct regulatory patterns. Most NAGs exhibited up-regulation under nitrogen stress, while diverse expression patterns were observed under salt and drought-nitrogen stress, indicating their crucial role in nitrogen assimilation and abiotic stress tolerance. These findings offer valuable insights into the genomic organization and expression profiles of GS, GOGAT, and NR genes in soybean under nitrogen and abiotic stress conditions. The results have potential applications in the development of stress-resistant soybean varieties through genetic engineering and breeding.

Precise counter anion modulation of the self-assembly behavior-endowed ultrasensitive and specific dual-mode visualization of nitrate.

Pt(II) polypyridine complex-based probe exhibits promising performance in anion detection by the change of the absorption and emission properties based on supramolecular self-assembly. However, whether one can develop a modulation strategy of the counter anion to boost the detection sensitivity and anti-interference capability of the Pt(II) complex-based probe remains a big challenge. Here, an effective modulation strategy was proposed by precisely regulating the interaction energy through adjusting the type of the counter anions, and a series of probes have been synthesized by counter anion (X = Cl-, ClO4-, PF6-) exchange in [Pt(tpy)Cl]·X (tpy=2,2':6',2''-terpyridine), and thus the colorimetric-luminescence dual-mode detection toward nitrate was achieved. The optimal [Pt(tpy)Cl]·Cl probe shows superior nitrate detection performance including a limit of detection (LOD) (8.68 nM), rapid response (<0.5 s), an excellent selectivity and anti-interference capability even facing 14 common anions. Moreover, a polyvinyl alcohol (PVA) sponge-based sensing chip loaded with the probe enables the ultra-sensitive detection of nitrate particles with an ultralow detection limit of 7.6 pg, and it was further integrated into a detection pen for the accurate recognition of nitrate particles in real scenarios. The proposed counter-anion modulation strategy is expected to start a new frontier for the exploration of novel Pt(II) complex-based probes.

Deciphering and quantifying nitrate sources and processes in the central Yellow Sea using dual isotopes of nitrate.

Anthropogenic activities pose significant challenges to the accumulation of coastal nitrogen (N). Accurate identification of nitrate (NO3-) sources is thus essential for mitigating excessive N in many marginal seas. We investigated the dual isotopes of NO3- in the central Yellow Sea to elucidate the sources and cycling processes of NO3-. The results revealed significant spatial variability in NO3- concentrations among the Yellow Sea Surface Water (YSSW), Changjiang Diluted Water (CDW), Yellow Sea Cold Water Mass (YSCWM), and Taiwan Warm Current Water (TWCW). Stratification played a crucial role in restricting vertical nutrient transport, leading to distinct nutrient sources and concentrations in different water masses. The dual NO3- isotopic signature indicated that atmospheric deposition was the primary source of surface NO3-, contributing approximately 30 % to the NO3- in the YSSW. In the NO3--rich CDW, the heavier δ15N-NO3- and δ18O-NO3- suggested incomplete NO3- assimilation. Organic matter mineralization and water stratification played crucial roles in the accumulation of nutrients within the YSCWM and TWCW. Notably, regenerated NO3- accounted for approximately half of the NO3- stored in the YSCWM. A synthesis of NO3- dual isotope data across the coastal China seas revealed significant spatial and seasonal variations in the N source. The study emphasized the dynamics of coastal NO3- supply, which are shaped by the complex interconnections among marine, terrestrial, and atmospheric processes. Our approach is a feasible method for exploring the origins of N amidst the escalating pressures of anthropogenic nutrient pollution in coastal waters.

Lanthanum nitrate demonstrated no genotoxicity in the conducted tests.

Given the widespread applications in industrial and agricultural production, the health effects of rare earth elements (REEs) have garnered public attention, and the genotoxicity of REEs remains unclear. In this study, we evaluated the genetic effects of lanthanum nitrate, a typical representative of REEs,with guideline-compliant in vivo and in vitro methods. Genotoxicity assays, including the Ames test, comet assay, mice bone marrow erythrocyte micronucleus test, spermatogonial chromosomal aberration test, and sperm malformation assay were conducted to assess mutagenicity, chromosomal damage, DNA damage, and sperm malformation. In the Ames test, no statistically significant increase in bacterial reverse mutation frequencies was found as compared with the negative control. Mice exposed to lanthanum nitrate did not exhibit a statistically significant increase in bone marrow erythrocyte micronucleus frequencies, spermatogonial chromosomal aberration frequencies, or sperm malformation frequencies compared to the negative control ( P > 0.05). Additionally, after a 24-hour treatment with lanthanum nitrate at concentrations of 1.25, 5, and 20 µg/ml, no cytotoxicity was observed in CHL cells. Furthermore, the comet assay results indicate no significant DNA damage was observed even after exposure to high doses of lanthanum nitrate (20 µg/ml). In conclusion, our findings suggest that lanthanum nitrate does not exhibit genotoxicity.

The Influence of Microstructure on TCR for Inkjet-Printed Resistive Temperature Detectors Fabricated Using AgNO3/Ethylene-Glycol-Based Inks.

This study investigated the influence of microstructure on the performance of Ag inkjet-printed, resistive temperature detectors (RTDs) fabricated using particle-free inks based on a silver nitrate (AgNO3) precursor and ethylene glycol as the ink solvent. Specifically, the temperature coefficient of resistance (TCR) and sensitivity for sensors printed using inks that use monoethylene glycol (mono-EG), diethylene glycol (di-EG), and triethylene glycol (tri-EG) and subjected to a low-pressure argon (Ar) plasma after printing were investigated. Scanning electron microscopy (SEM) confirmed previous findings that microstructure is strongly influenced by the ink solvent, with mono-EG inks producing dense structures, while di- and tri-EG inks produce porous structures, with tri-EG inks yielding the most porous structures. RTD testing revealed that sensors printed using mono-EG ink exhibited the highest TCR (1.7 × 10-3/°C), followed by di-EG ink (8.2 × 10-4/°C) and tri-EG ink (7.2 × 10-4/°C). These findings indicate that porosity exhibits a strong negative influence on TCR. Sensitivity was not strongly influenced by microstructure but rather by the resistance of RTD. The highest sensitivity (0.84 Ω/°C) was observed for an RTD printed using mono-EG ink but not under plasma exposure conditions that yield the highest TCR.